Large volumes of wastewater are generated in residential, municipal, industrial, and agricultural settings as a result of human activity. Waste streams generated by industrial and agricultural activities include a wide variety of contaminant materials including organic chemicals, inorganic compounds and elemental substances, and biological waste, as for example nitrogenous waste, thiols, mercaptans, and sulfides. A major limitation of present water treatment technology is the costly nature of managing volumes of wastewater. Ideally, wastewater treatment systems should be implemented at or very near the source of wastewater so as to avoid costs associated with transporting fluid waste.
Presently, aquaculture is a growing technology for food production. Aquaculture involves the farming of fish or other aquatic organisms under controlled conditions so as to maximize the quality and amount of food protein which can be generated in a given area. Aquaculture effluent is composed of animal waste and undigested feed including lipids, amino acids, proteins, minerals, polysaccharides, and ammonia (NH3) and ammonium ions (NH4+). Aquatic organisms experience toxic effects of elevated ammonia concentrations including gill damage, red blood cell damage, and a reduction in the blood's ability to carry oxygen, together with an increase in oxygen demand by tissue. Exposure to elevated levels of nitrogenous waste may be toxic to aquatic organisms, while exposure to lower levels can result in significant inhibition of growth and an increase in the incidence of disease. Hence, it is of paramount importance to control the levels of nitrogenous compounds in an aquaculture system.
Nitrogenous waste derived from aquaculture can be converted into a nutrient in connection with the growth of autotrophs such as green plants, algae, and other heterotrophic microorganisms, and such waste has been used successfully for the hydroponic cultivation of vegetation and microbes in a technology referred to as “aquaponics”. Conventional aquaponic techniques simply involve the application of nitrogenous wastewater streams to cultivated plots of growing plants. This approach consumes a large amount of space which could be utilized more efficiently for the production of aquaculture-derived protein. Furthermore, such techniques do not allow for the easy recovery of purified water for reuse in an aquaculture system. Consequently, the art has sought to implement compact, closed systems in which the plants are grown in a controlled environment which allows for introduction and removal of a fluid stream. However, such prior art systems require complex planter beds and are difficult to transport and utilize. Further, separation of individual plants, planters, or plant units from a hydroponic system and/or planter bed of the prior art without damaging the root system of the plant can be difficult. As a consequence, such technologies are not commercially feasible and do not lend themselves to a scale up and automation.
As will be explained in detail hereinbelow, the present invention is directed to a hydroponic wastewater treatment system which is modular and may be readily integrated with an aquaculture system. In that regard, the system may be reconfigured in size and shape as may be necessary during the growth and harvest cycle of the plants and/or aquatic organisms. The system of the present invention allows for complete control of the input and extraction of water from the hydroponic system and thus may be advantageously employed in locations and implementations where conservation of water is important. These and other advantages of the invention will be apparent from the drawings, discussion, and description which follow.